Mysql – Diagnosing Mysql Replication Issues

We have a mysql replication client running on our backup server. Since a power failure last week it's stopped replicating. Before this it was running uninterrupted for several months.

I've tried restarting both the master and the slave but this hasn't helped. I can access the master server from the slave, so the network isn't the issue.

Is there anything else I can do to try diagnose what the problem is?

mysql> show slave status\G;
*************************** 1. row ***************************
             Slave_IO_State:
                Master_Host: master
                Master_User: username
                Master_Port: 3306
              Connect_Retry: 60
            Master_Log_File: mysql-bin.000060
        Read_Master_Log_Pos: 46277494
             Relay_Log_File: mysqld-relay-bin.000348
              Relay_Log_Pos: 98
      Relay_Master_Log_File: mysql-bin.000060
           Slave_IO_Running: No
          Slave_SQL_Running: Yes
            Replicate_Do_DB:
        Replicate_Ignore_DB:
         Replicate_Do_Table:
     Replicate_Ignore_Table:
    Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
                 Last_Errno: 0
                 Last_Error:
               Skip_Counter: 0
        Exec_Master_Log_Pos: 46277494
            Relay_Log_Space: 98
            Until_Condition: None
             Until_Log_File:
              Until_Log_Pos: 0
         Master_SSL_Allowed: No
         Master_SSL_CA_File:
         Master_SSL_CA_Path:
            Master_SSL_Cert:
          Master_SSL_Cipher:
             Master_SSL_Key:
      Seconds_Behind_Master: NULL
1 row in set (0.00 sec)

ERROR:
No query specified


mysql> show master status\G;
*************************** 1. row ***************************
            File: mysql-bin.000069
        Position: 851796
    Binlog_Do_DB:
Binlog_Ignore_DB:
1 row in set (0.00 sec)

ERROR:
No query specified

Update: The errors were going into daemon.log, not mysql.err, which would explain why I couldn't find them. The problem seems to be that the master is saying the log is unavailable, which doesn't make much sense, because that log (and the previous one) are still available on the master.

090710  9:17:35 [Note] Slave SQL thread initialized, starting replication in log 'mysql-bin.000060' at position 46277494, relay log './mysqld-relay-bin.000350' position: 98
090710  9:17:35 [Note] Slave I/O thread: connected to master 'username@master:3306',  replication started in log 'mysql-bin.000060' at position 46277494
090710  9:17:35 [ERROR] Error reading packet from server: Client requested master to start replication from impossible position ( server_errno=1236)
090710  9:17:35 [ERROR] Got fatal error 1236: 'Client requested master to start replication from impossible position' from master when reading data from binary log
090710  9:17:35 [Note] Slave I/O thread exiting, read up to log 'mysql-bin.000060', position 46277494